A few Engine Q's

I have a few questions about the engine I'm working on. I've tried searching for pictures/diagrams but haven't found much so perhaps someone can point me in the right direction or answer my questions.
On my first picture I circled a few things.
1. ???? What is this thing- The PO obviously capped one outlet . . .
2. I have no tube running coming from the bottom my carb diaphragm. Should 1 and 2 be connected?
3. Is this supposed to be plugged? Looked a little odd to me ...
4. This is free floating; should it be? Part of the EGR assembly?
5. This is my temperature sending unit right?
6. What are these two little electrical connectors? just curious really...

In pic two, I labled three hoses that come off that "thing". I know the top one is the vaccuum advance, can the other two be interchanged? One runs to my carb, and the other to the mysterious #1 of the first pic.

I plan on getting a FSM once I establish that my engine is ok, I'm just a little hesitant to spend the 40 bucks right now
TIA for all the help- I'm on a steep learning curve...
Fred S

 

Hi Fred - I'd suggest you pony up for the manual now rather than later.
1) manifold vacuum tap, used for power brakes. 2) Nope. The diaphragm is the choke pulloff, and it's connected internally. No hose. 3) Looks like it goes into the manifold, but I can't see it well enough in the picture. Your manual would help... 4) Maybe an EGR delay valve - doesn't look original to me. 5) Yep. 6) That's the starter solenoid, and one of those comes from the ignition key (start = S) to energize the solenoid. The other provides power to the ignition (I) when starting - but I would have thought a '74 would not use the I wire. The only way to check is to look at the year-specific wiring diagram (FSM again).

The other is the spark CTO - basically a valve that changes from manifold to ported vacuum as the engine warms up. No, you can't change them.

 

4 = back pressure sensor for EGR valve; should be mounted under the EGR valve, then a metal tube supports the vac valve shown in the pic; this should be a one piece unit, the back pressure sensor that is.